And willis a



Reissued Feb. 7, 1928. Re.

UNITED STATES PATENT OFFICE.

ERNEST HOPKINSON, OF NEW YORK, AND WILLIS A. GIBBONS, OF LITTLE NECK, NEW YORK, ASSIGNORS TO REVERE RUBBER COMPANY, OF CHELSEA, MASSACHUSETTS, A CORPORATION OF RHODE ISLAND.

PROCESS FOR EMPLOYING WATER SOLUTIONS OF RUBBER AND ARTICLES SO PRODUCED.

No Drawing. Division of original No. 1,542,388, dated June 16, 1925, Serial No. 533,776, filed February 3, 1922. Application for reissue filed February 2, 1926. Serial No. 85,602.

DIVISION A.

This invention relates to processes for em- The invention accordingly consists in deploying water emulsions of rubber, that is positing a rubber article from rubber-conrubber latex or similar material either in its taining or similar latex on a surface and original state or concentrated or diluted; vulcanizing the article so deposited. 50

and to the articles so produced. By rubber-containing or similar latex is I Heretofore a restricted class of articles has meant juices or fluids producing rubber or been fabricated from rubber cements, that is balata or gutta percha either in its original solutions of crude rubber in benzol or similar state or concentrated or diluted as desired. solvent directly by dipping. An example As an example of a process for forming a 55 10 of such procedure is the formation of surgeons glove, whereby the alternate dipsurgeons gloves by dipping a form into a ping and drying on the form is eliminated, rubber cement, removing the form, allowing the following procedure may be carried out: the solvent to evaporate to form a thin coat- A form in the shape of a hand, made of ing of rubber on the form and alternately porous material, for example unglazed 1 dipping and drying the form and its adporcelain or china ware, is immersed in latex hering coating until a suflicient thickness of preferably that of Hevea brasile'ensils conrubber has been built up, whereupon the taining approximately 40-50% rubber and glove is stripped off and vulcanized. .Ap allowed to remain submerged to the proper proximately 5 alternate clippings and drydepth at ordinary room temperaturefor an ings are employed for the fabrication of the interval of time corresponding to the thickglove in this manner requiring a )proximateness of the rubber desired. 15 or minutes l v one day for the completion 0 the process is sufiicient for the manufacture of a and a number of handling or equivalent surgeons glove. The form is then withmechanical operations in moving forms into drawn from the liquid, allowed to drip and 25 and out of the cement. and the rubber thereupon is dried at room One of the objects of the present inventemperature or at a slightly elevated temtion accordingly is to provide a process for perature.

employing rubber latex or the like in which The withdrawal of water from the mass of fabrication of articles may be carried out by latex adjacent the form is effected through -3o one dipping or by fewer clippings than herethe pores of the porous material and causes toi'ore practiced with cements. Another oba segregation or collection of thickened latex ject is to provide a less expensive, less timeadhering to the form. This withdrawal of consuming process of the kind mentioned by Water takes place toward the interior of the eliminating various steps necessary to the form while the latter is immersed and upon manufacture of rubber cements and also withdrawal of the form elimination of water to eliminate the danger through fire or e: from the adherent mass takes place not only plosion and expense of organic solvents. towards the interior but also by ordinary Another object is to provide a process of the exterior evaporation. The drying of the kind mentioned wherein the fluid of the latex glove which has a thickness when dry of enclosed in the interior of a formor mold, .012" requires upproximately'one hour.

may be removed without opening the mold The love so produced is vulcanized prefduring the forming process. Another oberably y dipping; in the following solution: ject is to provide an article so fabricated of benzol parts by weight, zinc butyl tough, unmilled unhandled rubber having a xanthogenate 3 parts by Weight, dibenzylhigh tensile strength. greater resilience, and amine 3 parts by weight, and sulglg: 1 part greater resistance to wear. by weight. The proportions of t it will employed or be. understood may lie-varied depending on the conditions of'vulcanization desired. An immersion of-one or two minutes at room temperature followed by air drying and vulcanization for 1 hr. at 212 F produces a satisfactorily vulcanized article, or after dipping if the glove is allowed to stand for approximately 3 weeks vulcanization is satisfactorily accomplished. In any event the glove is then treated with stripped from the form in the usual way. In place of the vulcanization rocess mentioned sulphur-chloride-vapor-vu canization may be vulcanization by dipping in a solution of sulphur chloride may be used with satisfactory results; or other known vulcanization methods may be utilized.

It will be observed that the process described is one which utilizes rubber latex direct, that is the rubber is deposited on the form directly. There is no necessity as in the old rocess of cement-making to coagulate, mil wash and dissolve the nubberprior to its use. It has been found that the rate of deposition of the rubber on the form varies with the time of immersion, and the thickness of the. deposit lessens for successive equal intervals of time regardless of the nature of the absorbent medium. The length of drying the coating deposited on the form it will be observed is approximately the same as required for one drying of cement deposited on the usual form. By causing the operation to take place in a single dipping, it will be readily realized that much labor is saved compared with the cement-dipping process.

It will be observed that although latex havin a rubber content of 40-50% is indicate in the preferred example, normal latex containing for example 30% rubber may be employed, or more concentrated or more dilute latex as desired. It has been found that the rate of deposit of rubber on the form is substantially constant where the rubber content of the latex is 30 or 40 or In other words the rate of deposit appears substantially unaffected by the rub-. ber content of the latex.

As an alternative to the process described above the following process may be carried out :-'A mold of porous material made for example in two sections within which is a cavity, for example in the shape of a hot water bottle, is fil ed with latex, the two sections being tightly pressed together, and allowed to stand for a time suflicient to form on the interior surface a coating of the desired thickness. A assage is provided in the mold through which latex may be ured into the interior cavity and which wi 1 form a neck for the hot water bottle. When sufficient rubber has been deposited on the inside of the mold the iemainin liquid which i is now enclosed in a sack of eposited rubtalc and.

be made smooth by polishing or immersing her is poured out throu h the opening provided at the neck of t 1e hot water bottle and the deposit is dried at ordinary or elevated temperature and vulcanized as herein before set forth or in any desired manner.

Substantially any porous material capable of sucking up water by capillarity appears to be able to deposit latex on its surface, and to ermit its removal therefromr Where the article is to be removed from the form or mold the pores are of a size such that rubber particles may not pass to an a preciable distance into the mold, since if t is action occurs it will be found diflieult or impossible to remove the rubber coating. course it should not be porous to an ex tent such that the latex as a whole may pass through it. Surfaces which are satisfactorily absorbent but not sufficiently smooth can them in a suspension of finely powdered china clay or similar porous material in finely powdered form with a subsequent drying of china clay or other coating on the form. Instead of this dipping, the clay or other material may be rubbed or brushed on to the form. In place of the unglazed porcelain or china mentioned above the material known as sllocel may be employed for making the desired forms. This is a natural deposit of tightly compressed diatomaceous earth.

Many of the water'soluble constitutents of the latex are withdrawn in solution from the latex into the interior of the porous form employed so that the deposit of rubber on the surface is lower in protein and salt content than would be obtained if the latex were evaporated down with all these constituents. The soluble constituents drawn into the form may be washed out by immersion of the form in fresh water or by any other desired means such as by heating or chemicals. In the case of glove forms a simple immersion in plain water is sufficient, the water soluble constituents passing through the form which is hollow into the interior cavity from which they'may be poured out, the form then being dried at an elevated temperature.

A modification of the procedure consisting in filling the cavity with latex consists in introducing sufficient latex to give an article for example a water bottle the desired wall thieknesswithout leaving an excess of latex on the interior of the bottle at the time 12" when a deposit of the required thickness is obtained. In other words the quantity of latex employed has a rubber content just sulficient to provide the article and the fluid of the latex passes substantially. entirely 12 into the Eprous material leaving an empty article he 'nd. In carrying out the process with just sullicient latex for the formation of the article the mold is preferably slowly rotated about a horizontal axis so that tlvrubber may be evenly deposited over the entire surface. Rotation of course may be employed in the case where an excess of latex is used as above described.

It has been found that the deposit of rubber made by the immersion of porous materials in latex serves as a convenient means for concentrating the latex and obtaining a substance which may be recouverted into the original latex by simple addition of water. In other words the deposit on the surface of the porous material if placed in water will return to latex. Pressure of the particles or agitation in forming the deposit on the form prior to their immersion in the water should be avoided as such action tends to cause the deposit to form a mass which upon addition of water may be partially or wholly incapable of being converted into latex. The material removed from the porous surface contains normally 80-85% of rubber.

In place of the porous forms described above, glazed forms may be employed for example a glazed form similar to that ordinarily used in the dipping process employing cements. In carrying out such a process its preferred form latex, preferably con ntrated by evaporation to a rubber content of 50-55%, is employed. To this solution a gelatine solution having a gelatine content of 1 2% based on the weight of the rubber content of the latex is added, along with suflicient water to bring the rubber content to -45% approximately. The gelatine increases the viscosity of the latex and aids in the dipping process. The viscosity may be altered as will be observed by concentrating or diluting the solution of latex and gelatine. Into this mixture the glazed form is dipped and Withdrawn. The coated form is shaken or otherwise mechanically treated to remove the excess liquid. It is then rapidly turned so that the fingers are uppermost and dried. Drying may be accomplished at room temperature or!" at slightly elevated temperature, preferably not exceeding 40 C. The coated form after drying is given two further dippings and alternate dryings in case of the manufacture of a surgeons glove. After the second dipping the form is suspended with the lingers downward and after the third dipping it is again rapidly placed with the lingers upward for the drying process. Three'dips will provide a structure of .010 to .012 inches providing a medium weight surgeons glove.

The glove after drying is preferably dipped in a solution like that employed for vulcanizing the glove made on the porous form.

For the manufacture of sheet rubber from latex an endless belt rotating over rollers suitably spaced apart may be employed. The belt passes through a tank or other receptacle containing latex receiving a coating thereof which is dried and stripped from the belt surface to form a rubber sheet. If desired a series of such clippings and dryings may be alternately made in order to increase the thickness of the sheet. Compounding, vulcanizing and other ingredients may be employed with the latex if desired or may be applied subsequent to the forming of the sheet.

' The latex employed in carrying out the various processes is preferably that which has been preserved by addition of ammonia, formaldehyde or other stabilizer or preservative, but if desired a latex free from such materials may also be employed containing 20 to 35% rubber. In place of this ordinary latex, however, one that has been concentrated to any desired extentfor example by evaporation may be employed. In the case of employment of glazed forms a concentrated latex having approximately 40% rubber by weight is employed. i

The latex employed may be mixed with any softening, coloring, accelerating or vulcanizing ingredients.

Where substances are admixed it is preferred to keep the latex with the added material in agitation. This may be satisfactorily accomplished in the case of articles formed on the interior of a mold as above described by rotation of the mold.

It will be observed that the processes de scribed eliminate the alternate dipping and drying process heretofore practiced with cement or such dippmgs and dryings carried out. The use of explosive and inflammable solvents such for example as benzol heretofore used in connection with cements is also avoided by the processes mentioned. Furthermore the expensive and time-consuming processes heretofore required for the preparation of crude rubber involving coagulation of the latex, its washing, drying, baling and subsequent milling for its solution in the solvent, benzol or the like, is avoided. In the case of the deposit of rubber on the interior of the mold it will be seen that the fluid is conveniently removed without manipulation of the mold, that is without opening it to remove fluid during the forming process. The procedures outlined are thus simple and inexpensive and greatly reduced the labor necessary for the formation of various articles heretofore manufactured from cements. The articles manufactured by the processes have in general superior characteristics to similar articles heretofore manufactured from cements in that they are made of tough, unmilled rubber which possesses a high tensile strength, greater resilience and greater resistance to wear. In addition to the articles mentioned there may be made by the processes set forth inner tubes. tobacco pouches, nipples, bulbs, playing balls, balls for floats,

greatly restricting the number of l5 ric either 20 objects :35 pressure on the composition.

50 which comprises continuous by maintaining the form in 55 which coinp pure gum tubing, overshoes and various others. An inner tube or other rubber article made according to the present invention has no grain, its ph sicalcharacteristics 5 being substantially uniform in all directions. The tearing strength of an article made according to the present invention is substantially greater than corresponding articles made from rubber which has been milled. It will be obvious that various man- 2 limit ourselves to the specific embodiment herein set forth except as indicated in the appended claims. In the claims the expression non-molded refers to the absence of a confining mold such as that commonl used in molding rubber articles to shape; T e applicants initially assemble the constituent particles of the article directly from an aqueous dispersion and without any confining mold exerting a shaping or compacting In the claims also the expression rubber latex is used broadly to comprehend any form thereof and particularly whether or not it is compounded with filling, vulcanizing and/or accelerating ingredients.

Having thus described our invention, what we claim and desire to protect by Letters Patent is 1. The method of making rubber articles 4.: which comprises continuously depositing on a form solids from a body of latex while maintaining the form in contact withsaid body, and drying and vulcanizing the article. 2. The method of making rubber articles y building up a deposit of rubber solids on a form by ising the surface of the form in contact with a body of latex, withdrawing moisture from that portion of the latex in contact with the form, and drying and vulcanizing the article.

3. The method of making rubber articles which com rises continuously building up a deposit 0 rubber solids on a porous fogn contact with a body of latex and withdrawing moisture through the form, and drying and vulcanizing the article. a

4. The method of making rubber articles rises gradually and continuously rubber latex on building up a de sit from latex ofrubber having substantia ly and t e thickness desired, and vulcanizing the rubber. i

5. The method of making rubber articles which comprises radually and continuously building up by a rption of moisture 'a deposit from latex of rubber having substantially the shape of the article desired, and vulcanizing the rubber.

6. A process for treating latex which comprises continuously depositing rubber from latex on a porous form to form a rubber article and vulcanizing the article so deposited.

7. A process for treating latex which comprises immersing a porous glove form in la tex, allowing the form to remain immersed until a glove of suflici-ent thickness has been built up on the form, drying the glove so produced, and vulcanizing the love.

8. The method of making ru ber articles which consists in continuously segregating solids from a body of latex on the surface of a form of desired contour by withdrawing moisture from the latex at said surface until the desired thickness of deposit is obtained, withdrawin the form from the latex and drying the fie 9. A hollow vulcanized article gradually built up on a form as a continuous deposit of rubber from latex.

10. The method of making rubber articles which comprises coating a porous form with a suspension of porous material to render its posit, and vulcaniz-.

the shape of the article surface smoother, depositing rubber from the coated porous form by withdrawing moisture from the latex into the form, drying the deposit on the form in the shape of the article desired, and vulcanizing the article.

11. A hollow vulcanized non-laminar rubher article having a greater resistance to tearing than the same vulcanized rubber ar ticle made of milled rubber, the resistance totearing being substantially the same in all directions.

12. A' hollow vulcanized non-laminar rubher article without grain and 'havin physical characteristics substantially uni cm in all directions.

13; A hollow vu canized non-laminar rubber article: without grain the constituent particles of which have been initially assembled together directly from an aqueous dispersion. v

14. A hollow vulcanized non-laminar nonmohlcd rubber article without grain and having substantially uniform physical characteristics in all directions.

15. The step in the process of forming rubber articles which comprises gradually and continuously building up a non-laminar deposit of rubber from latex b withdrawal of its aqueous portion and wit out altering z; of water through the porous the percentage of solids in the latex from which the deposit is built.

16. A on a porous form entirely by absorption orm from a body of rubber latex while theform is in contact therewith.

17. The method of makin hollow rubber articles which includes app ying a body of rubber latex to the surface of a porous form, withdrawin the aqueous portion of the latex through the form and collecting the dispersed solid particles of the latex .on its surface to build up the walls of the article, removing the porous form thus coated with rubber from contact with the remaining body of latex, and completely drying and suitably vulcanizing the article.

18. In the direct manufacture of hollow rubber articles from rubber latex, the steps of, applying a'body of rubber latex to the surface of a porous form, withdrawing the aqueous portion of the latex through the form and collecting the dispersed solid particles of the latex on its surface to build up non-laminar rubber article built upthe article, removing the form thus coated with rubber from the remaining body of latex, and subsequently repeating the opera tions with one or more forms and the said remaining body of latex.

19. The method of makin hollow rubber articles which includes app ying a body of rubber latex to the surface of a porous form, withdrawing the aqueous portion of the latex throu h the form and collecting the dispersed sofid particles of the latex on its surface to build up the walls of the article, removing the porous form thus coated with rubber from contact with the remaining body of latex, and completely drying and suitably vulcanizing the article, the said remaining body of latex being substantially the same as that initially applied to the surface of the porous form.

Signed at New York, New York, this 1st day of February, l926. v

ERNEST HOPKIN SON. Si ned at New York, New York, this 1st day ebruary, 1926.

' WILLIS A. GIBBON S.

DlSOLAlMER Re. No. 16,873.-Emest Hopkinson, New York, and I Villis A. Gibbons, Little Neck, N. Y. PRocEss FOR EMPLOYING WATER SOLUTIONS OF RUBBER AND ARTICLES so PRODUCED. Patent dated February 7, 1928. Disclaimer filed February 25, 1939, by the assignee, United States Rubber Company.

Hereby disclaims from the scope of each of claims 11, 12, 13, and 14, hollow articles having a minimum wall thickness of .004 inch or less.

[Oflim'al Gazette March 21, 1939.] 

